Editing Numbers station (section)

== Formats ==
[[File:Russian Man signoff 2013-04-23.ogg|thumb|The "Russian Man" station signing off. The numbers read: 83912 83912 10080 10080 46543 46543{{spnd}}257 257 143 143{{spnd}}000 00]]
Generally, numbers stations follow a basic format, although there are many differences in details between stations. Transmissions usually begin on the hour or half-hour.{{citation needed|date=December 2015}}

The prelude, introduction, or call-up of a transmission (from which stations' informal nicknames are often derived) includes some kind of identifier,<ref name="Numbers Stations">{{cite web |url=https://www.numbers-stations.com/ns/ |title=Intro to Numbers Stations |date=8 February 2016 |access-date=12 March 2016 |publisher=NSRIC |df=dmy-all}}</ref> for the station itself, the intended recipient, or both. This can take the form of numeric or [[spelling alphabet|radio-alphabet]] "code names" (e.g. "Charlie India Oscar", "250 250 250", "Six-Niner-Zero-Oblique-Five-Four"), characteristic phrases (e.g. "¡Atención!", "Achtung!", "Ready? Ready?", "1234567890"), and sometimes musical or electronic sounds (e.g. "The Lincolnshire Poacher", "Magnetic Fields"). Sometimes, as in the case of radio-alphabet stations, the prelude can also signify the nature or priority of the message to follow (e.g., it may indicate that no message follows). Often the prelude repeats for a period before the body of the message begins.{{citation needed|date=December 2015}}

After the prelude, there is usually an announcement of the number of number-groups in the message,<ref name="Numbers Stations" /> the page to be used from the one-time pad, or other pertinent information. The groups are then recited. Groups are usually either four or five digits or radio-alphabet letters. The groups are typically repeated, either by reading each group twice or by repeating the entire message as a whole.{{citation needed|date=December 2015}}

Some stations send more than one message during a transmission. In this case, some or all of the above process is repeated, with different contents.{{citation needed|date=December 2015}}

Finally, after all the messages have been sent, the station will sign off in some characteristic fashion. Usually, it will simply be some form of the word "end" in whatever language the station uses (e.g., "End of message; End of transmission", "Ende", "Fini", "Final", "конец"). Some stations, especially those thought to originate from the former Soviet Union, end with a series of zeros, e.g., "00000" "000 000"; others end with music or other sounds.<ref name="Numbers Stations" />

Because of the secretive nature of the messages, the [[cryptography|cryptographic function]] employed by particular stations is not publicly known, except in one (or possibly two){{efn|In the possible case, the underlying type of encryption might have been stated in the court record of the Atención case when the secretly copied decryption software was introduced into evidence.}}) cases. It is assumed that most stations use a one-time pad that would make the contents of these number groups indistinguishable from randomly generated numbers or digits. In one confirmed case, West Germany did use a one-time pad for numbers transmissions.<ref>{{cite web |last1=Wagner |first1=Thomas |title=If it had not been for 15 Minutes, Chapter 7 |url=http://radio-weblogs.com/0101986/stories/2002/12/08/ifItHadNotBeenFor15MinutesChapter7.html |website=Radio Weblogs |access-date=18 March 2022 |archive-url=https://web.archive.org/web/20131102124519/http://radio-weblogs.com/0101986/stories/2002/12/08/ifItHadNotBeenFor15MinutesChapter7.html |archive-date=2 November 2013 |date=8 December 2012 |url-status=live}}</ref>